Need opinion about our (C# WinForm) project

Question

so we have a project, well the project's actually finished already. our task is to maintain/upgrade/recode some module that needs to.

but see, the project now has about 15~20 modules in it. and it's all in a single project. which i believe will be a pain in the ass.

i was thinking of, instead of making tons of folders per module, and tons of forms in the project. why not just make a single .dll per module ?. i've thought of this thinking:

-with one dll per module, we're saving time of compiling or rebuilding the whole project. with a dll, we'll just be modifying a single, independent module. so whatever goes wrong, the whole project won't be affected.

-after the modification, upgrade, or enhancement is done, all we have to do is copy/paste that dll to the project's executable directory, replacing the old dll. this way, the deployment would be easier, better, and less of an effort.

-i think this is a more professional way of tackling the project. by just making a single executable with tons of forms inside of it, makes the system bloated, or can slow the system down. as far as i believe.

so those are the things i've had in mind for quite a time now.

if anyone can agree or not with me on here, please tell me. i just want to know what's best for this project. thank you.